1. Field of the Invention
The present invention relates to a substrate manufactured from sheet metal and a resin. Specifically, the present invention relates to a substrate provided with a wiring pattern and a land for soldering wire thereon. Further, the present invention relates to a motor provided with the substrate and a soldering method for connecting the tip of the wire to the land of the substrate.
2. Description of the Related Art
Japanese Patent Laid-Open No. 11-68289 discloses one method for automatically soldering the tip of a wire to the land of a substrate by flow soldering. Flow soldering is a method of connecting the wire to the land of a substrate by immersing the surface of the substrate provided with the land into a solder bath of molten solder. However, if the substrate is made of a resin, the heat resistance of the resin may result in that the substrate cannot be immersed in the solder bath. In such cases, in order to prevent the deformation of the substrate due to heat; it is necessary to solder a wire onto each land. Accordingly, a method of, for example, attaching a soldering iron to a robot hand, moving the tip of the soldering iron to each of the lands on the substrate, and soldering the tip of the wire to each land is adopted.
FIG. 7 is a top view of a conventional substrate, and FIG. 8 is a cross-section of the substrate taken along the line X-X′ in FIG. 7.
When manufacturing a substrate having lands thereon, a resin is integrally molded with a sheet metal such that a portion of the sheet metal does not have the resin molding carried out thereon, thereby remaining exposed. Consequently, as illustrated in FIGS. 7 and 8, the exposed surface of the sheet metal 11 is used as the land 13. In this case, a resin wall 12 perpendicular to the land 13 is formed around the land 13 to which a wire 14 is to be soldered. In a substrate 15 provided with the land 13 shaped as such, as described above, when moving the tip of a soldering iron to the land 13 by a robot, there is a risk that the tip of the soldering iron may contact the resin wall 12 around the land 13 resulting in damage to the resin wall 12.
This problem occurs, when the tip of the soldering iron is not accurately moved to the center of the land and may be caused by, for example, misalignment of the substrate to be soldered, or teaching an inaccurate target position to the robot, etc. This problem becomes more pronounced the smaller the surface area of the land.
Further, as a method of soldering without the use of a soldering iron, a laser may be used (hereinafter referred to as laser soldering). In laser soldering, a laser beam can be focused onto a small spot, thus it is possible to solder a land with a small surface area. However, when laser soldering is carried out on the land 13 of the substrate 15, illustrated in FIGS. 7 and 8, there is a problem that diffuse reflection of the laser beam from the land 13 may irradiate the resin wall 12 surrounding the land 13, melting the resin wall 12, and when the laser beam is impinged upon the wire 14 to be soldered, diffuse reflection of the laser beam may occur and cause the resin wall 12 to melt. This problem becomes more pronounced the smaller the surface area of the land.
It is desirable for the resin surrounding the land to be resistant to damage by diffuse reflection of a laser beam, and for the area which is soldered in order to suppress diffuse reflection of a laser beam, when a resin molded substrate is laser soldered.